基于正交试验的聚甲醛纤维机场道面混凝土力学性能研究

Study on Mechanical Property of Airport Pavement Concrete with POM Fiber Based on Orthogonal Test

为确定聚甲醛(POM)纤维长度和掺量对机场道面混凝土力学性能的影响机制,利用L_(9)(3^(3))正交表设计了9组正交试验组,主要研究3种不同水胶比、3种POM纤维长度、3种POM纤维掺量对机场道面混凝土抗压及抗弯拉强度影响的显著性。基于正交试验强度敏感性分析结果,进一步分析了POM纤维长度和掺量对机场道面混凝土力学性能的影响。结果表明:基准组试件在荷载到达限度后迅速降低,表现出脆性损坏特点,而POM纤维增强组试件的裂纹扩展较慢,表现出一定的延性损坏特点,POM纤维能够有效抑制混凝土裂纹的扩展,改善混凝土脆性,起到增韧的作用;与基准组相比,纤维增强组抗压强度和抗弯拉强度分别在0.6%~10.1%和15%范围内波动,纤维长度和掺量的改变并不能引起混凝土抗压和抗弯拉强度发生显著变化;POM纤维长度和掺量对机场道面混凝土主要控制指标28 d抗弯拉强度的影响远小于水胶比,纤维掺量对力学性能的影响小于纤维长度,且难以通过邓肯氏检验确定3个因素的最优水平;POM纤维对机场道面混凝土残余抗弯拉强度(韧性)有显著提升,12 mm POM纤维在1.2%混凝土体积掺量时对韧性提升效果最优,并据此认为其对机场道面混凝土28 d抗弯拉性能改善效果最好。

In order to determine the influence mechanism of polyoxymethylene(POM)fiber length and content on mechanical properties of airport pavement concrete,9 orthogonal test groups are designed by using L_(9)(3^(3))orthogonal table,the effects of 3 kinds of water-binder ratio,3 kinds of POM fiber length and 3 kinds of POM fiber content on the compressive and flexural strength of airport pavement concrete are studied.Based on the strength sensitivity analysis of the orthogonal test,the influence of the length and content of POM fiber on the mechanical properties of airport pavement concrete is further analyzed.The result shows that(1)the crack growth of the reference specimen decreases rapidly after the load reaches the limit,and the specimen shows brittle failure,while the crack growth of the POM fiber reinforced specimen is slower,and the specimen shows certain ductile failure,POM fiber can effectively restrain the expansion of concrete cracks,improve the brittleness of concrete and play a toughening role;(2)compared with the reference group,the compressive strength and flexural strength of the fiber-reinforced group fluctuate within 0.6%-10.1%and 15%respectively,the change of fiber length and content cannot cause significant change of compressive strength and flexural strength of concrete;(3)the effect of POM fiber length and content on the 28 d flexural strength of airport pavement concrete is much less than that of water-binder ratio,and the effect of fiber content on the mechanical properties is less than that of fiber length,and it is difficult to determine the optimal level of the 3 factors by Duncan test;(4)POM fiber can significantly improve the residual flexural strength(toughness)of airport pavement concrete,and 12 mm POM fiber has the best effect when 1.2%concrete volume is added,based on that,it is considered the best way to improve the bending and tensile properties of 28 d airport pavement concrete.